In conventional cameras, an image of a scene to be captured is reproduced on an image sensor, for example a CCD sensor a CMOS sensor, via a lens. The lens may be a so called fixed focus lens where a focus plane has a fixed distance from the lens or may be a variable focus lens where the position of the focus plane may be varied. Objects in or adjacent to the focus plane appear “sharp” in the image captured by the image sensor, while objects outside or farther away from the focus plane appear more or less blurred. Depending on an aperture used, an area where objects appear sharp in the captured image may extend to some distance on both sides of the focus plane. In such a conventional camera, the position of the focus plane and the sharpness of the recorded image may only be influenced by post processing in a very limited manner. It should be noted that depending on the lens used, the focus plane need not be an actual plane, but may also be curved.
A new type of camera which has been developed and researched in recent years is the so called computational camera. In computational cameras, the image is not directly reproduced on the image sensor, such that essentially, apart of operations like demosaicing and sharpening, the output of the image sensor directly shows the captured scene, but light rays from the scene in computational cameras are guided to an image sensor in an unconventional manner. For example, light rays originating from a single object in the scene to be captured may be guided to different locations remote from each other on an image sensor, which corresponds to viewing the object from different directions. To this end, for example a conical mirror may be arranged in front of a lens. In other implementations, an optic used for guiding light from a scene to be recorded to the image sensor may be variable, for example by varying geometric or radiometric properties. Such a variable optic may for example comprise a two-dimensional array of micro mirrors which have controllable orientations.
Unlike conventional cameras, in computational cameras a more sophisticated processing of the data captured by the image sensor is necessary to provide the final image. On the other hand, in many cases there is a higher flexibility in setting parameters like focus plane of the final image.
It is an object of the present invention to exploit the possibilities such computational cameras offer.